1. Field of the Invention
The present invention generally relates to a calendar timepiece. Particularly, the invention relates to a timepiece with a calendar which incorporates a movement having a small-sized and thin-sized construction.
2. Description of the Prior Art
(1) Conventional Calendar Mechanism Disclosed in Patent Literature 1: JP-A-10-104365 (Pages 3–5, FIG. 1)
According to a conventional timepiece with calendar, an hour wheel is brought in mesh with an intermediate date indicator driving wheel of an intermediate date indicator driving wheel & pinion. An intermediate date indicator driving pinion of the intermediate date indicator driving wheel & pinion is brought in mesh with a date indicator driving wheel. A date indicator is rotatably integrated to a main plate. The date indicator is rotated by a date indicator driving finger of the date indicator driving wheel. The date indicator driving wheel includes the date indicator driving finger for rotating the date indicator and a day indicator driving finger for rotating a day indicator. A date indicator setting portion of a date jumper is engaged with an inner teeth portion of the date indicator to set rotation of the date indicator. A date jumper spring portion of the date jumper is extended in a direction reverse to a direction of rotating the date indicator with the date indicator setting portion as a reference (for example, refer to Patent Literature 1).
(2) Conventional Calendar Mechanism Disclosed in Patent Literature 2: JP-UM-A50-76863 (Pages 2–5, FIG. 1)
Further, according to another conventional timepiece with calendar, a calendar feed member having a calendar feed finger engaged with a cam provided at a date indicator driving wheel is urged in accordance with shift of an engagement point from a lower portion to a higher portion of the cam. Further, the calendar feed finger drives a calendar indicating member by an amount of one date by rotating the calendar feed member by discharging a biasing force when the engagement point is rapidly shifted from a highest portion to a lowest portion of the cam (for example, refer to Patent Literature 2).
(3) Conventional Calendar Mechanism Disclosed in Nonpatent Literature 1: “The Theory of Horology” by Charles-Andre Reymondin et al., The Swiss Federation of Technical Colleges. 1999. Pgs. 194–198.
Further, according to another conventional calendar mechanism of a timepiece, a 24 hour wheel operates a date lever. A pin of the date lever is pressed to a tooth portion of a date indicator by a return spring. A date lever spring presses the date lever to a finger of the 24 hour wheel. At midnight, the finger of the 24 hour wheel leaves a front end of the date lever and the date lever is swiftly returned to an original position by the return spring. At this occasion, the pin of the date lever rotates the date indicator (see, for example, nonpatent literature 1).
(4) Other Conventional Calendar Mechanisms:
(4•1) Structure of Calendar Apparatus
With reference to FIG. 24 and FIG. 25, according to another conventional calendar mechanism, a date indicator 920 is rotatably integrated to a main plate 902 on a back side (dial side) of a movement. A date indicator driving finger 930 is integrally provided with a date indicator driving wheel 906. The date indicator driving finger 930 rotates the date indicator 920 by rotating the date indicator driving wheel 906. A date indicator setting transmission wheel 912 is brought in mesh with a date corrector setting wheel 914. The date corrector setting wheel 914 is pivotably integrated to a circular arc long hole 902h of the main plate 902. A date corrector cam 916 is integrally provided with the date corrector setting wheel 914. Referring to FIG. 25, when the date corrector setting wheel 914 is disposed at a first position pivoted in one direction in a state in which a winding stem 910 is disposed at 1 stage, the date corrector cam 916 is brought in mesh with an inner teeth portion 920a of the date indicator 920. When the date corrector setting wheel 914 is disposed at a second position pivoted to other direction, the date corrector cam 916 is not brought in mesh with the inner teeth portion 920a of the date indicator 920. In the state in which the winding stem 910 at 1 stage, the inner teeth portion 920a of the date indicator 920 can be rotated by the date corrector cam 916 by rotating the date corrector setting wheel 914 and the date corrector cam 916 via rotation of the date indicator setting transmission wheel 912.
In reference to FIG. 24 and FIG. 25 and FIG. 29, a date jumper 940 is provided at the main plate 902. The date jumper 940 includes a base portion 941, a date indicator setting portion 942 and a date jumper spring portion 944. The base portion 941 is fixed to the main plate 902. The date indicator setting portion 942 of the date jumper 940 is engaged with the inner teeth portion 920a of the date indicator 920 to set rotation of the date indicator 920. In FIG. 24, a rotating direction of the date indicator 920 is the clockwise direction.
(4•2) Structure of Date Feeding Mechanism
In reference to FIG. 24 and FIG. 29, the date indicator driving wheel 906 is rotatably integrated to the main plate 902. The date indicator driving finger 930 includes a central portion 931 integrally provided to the date indicator driving wheel 906, a spring portion 932 in a shape of a circular arc extended from the central portion 931 and a date indicator feeding portion 933 for rotating the date indicator 920. A clearance 931b is provided between an inner peripheral portion of the spring portion 932 and an outer peripheral portion of the central portion 931. As shown by an arrow mark in FIG. 29, the date indicator 920 is rotated in the clockwise direction. Similarly, as shown by an arrow mark in FIG. 29, also the date indicator driving wheel 906 is rotated in the clockwise direction.
In reference to FIG. 29, FIG. 29 shows a state in which the date indicator feeding portion 933 of the date indicator driving finger 930 is rotated along with the date indicator driving wheel 906 and is just brought into contact with the inner teeth portion 920a of the date indicator 920. The state is defined as a state in which a date indicator rotating angle is 0 degree, that is, “state of point A” in FIG. 28.
The inner teeth portion 920a of the date indicator 920 includes 31 pieces of trapezoidal teeth. A preceding tooth in view of the rotating direction of the date indicator 920 in the inner teeth portion 920a of the date indicator 920 with which the date indicator setting portion 942 of the date jumper 940 is brought into contact is defined as a first tooth 920f and a succeeding tooth is defined as a second tooth 920g. 
The date indicator setting portion 942 of the date jumper 940 includes a first setting portion 942a and a second setting portion 942b. In a state shown in FIG. 29, the first setting portion 942a is brought into contact with a circular arc at a tooth tip of the first tooth 920f and the second setting portion 942b is brought into contact with a circular arc of a tooth tip of the second 920g. 
(4•3) Operation of Date Indicator Feeding:
When the date indicator driving wheel 906 and the date indicator driving finger 930 are rotated further from the state shown in FIG. 29, the clearance 931b between the inner peripheral portion of the spring portion 932 of the date indicator driving finger 930 and the outer peripheral portion of the central portion 931 is narrowed to bring about a state shown in FIG. 30. FIG. 30 shows “state of point B” in FIG. 28. From the state shown in FIG. 29 to the state shown in FIG. 30, the first setting portion 942a of the date jumper 940 stays to be brought into contact with the circular arc of the tooth tip of the first tooth 920f and the second setting portion 942b stays to be brought into contact with the circular arc of the tooth tip of the second tooth 920g. Therefore, from the state shown in FIG. 29 to the state shown in FIG. 30, the date indicator 920 is not rotated.
When the date indicator driving wheel 906 and the date indicator driving finger 930 are further rotated further from the state shown in FIG. 30, the date indicator driving finger 930 rotates the date indicator 920 in a direction shown by an arrow mark to bring about a state shown in FIG. 31. FIG. 31 shows “state of point C” in FIG. 28. In the state shown in FIG. 31, the clearance 931b between the inner peripheral portion of the spring portion 932 of the date indicator driving finger 930 and the outer peripheral portion of the central portion 931 stays to be narrowed. From the state shown in FIG. 30 to the state shown in FIG. 31, the first setting portion 942a of the date jumper 940 leaves the tooth tip of the first tooth 920f and the circular arc of the tooth tip of the second tooth 920g slides along the second setting portion 942b. Therefore, in the state shown in FIG. 31, the circular arc of the tooth tip of the second tooth 920g is brought into contact with the second setting portion 942b immediately before an intersection of the first setting portion 942a and the second setting portion 942b. When the date indicator 920 is rotated from “state of point B” to “state of point C” in FIG. 28, date indicator feeding resistance is increased.
When the date indicator driving wheel 906 and the date indicator driving finger 930 are further rotated further from the state shown in FIG. 31, the date indicator driving finger 930 rotates the date indicator 920 in a direction shown by an arrow mark to bring about a state shown in FIG. 32. FIG. 32 shows “state of point D” in FIG. 28. In the state shown by FIG. 32, the clearance 931b between the inner peripheral portion of the spring portion 932 of the date indicator driving finger 930 and the outer peripheral portion of the central portion 931 stays to be narrowed. That is, the state is a state in which a force for rotating the date indicator 920 is stored in the date indicator driving finger 930.
From the state shown in FIG. 31 to the state shown in FIG. 32, the intersection of the first setting portion 942a and the second setting portion 942b of the date jumper 940 slides on a linear portion of the trapezoidal tooth tip of the second tooth 920g. When the date indicator 920 is rotated from “state of point C” to “state of point D” in FIG. 28, the date indicator feeding resistance is rapidly reduced. That is, between “state of point C” and “state of point D” in FIG. 28, the force for rotating the date indicator 920 stored in the date indicator driving finger 930 becomes much larger than a force necessary for rotating the date indicator 920 (that is, date indicator feeding resistance) and the date indicator 920 starts rotating rapidly.
When the date indicator driving finger 930 is further rotated from the state shown in FIG. 32, the date indicator driving finger 930 rotates the date indicator 920 in a direction shown by an arrow mark to bring about a state shown in FIG. 33. FIG. 33 shows “state of point E” in FIG. 28. The date indicator feeding resistance in rotating the date indicator 920 from “state of point D” to “state of point E” in FIG. 28 is the force necessary for rotating the date indicator 920. In the state shown in FIG. 33, the clearance 931b between the inner peripheral portion of the spring portion 932 of the date indicator driving finger 930 and the outer peripheral portion of the central portion 931 is widened. From the state shown in FIG. 32 to the state shown in state shown in FIG. 33, the intersection of the first setting portion 942a and the second setting portion 942b of the date jumper 940 slides on the linear portion of the trapezoidal tooth tip of the second tooth 920g. When the date indicator 920 is rotated from “state of point D” to “state of point E” in FIG. 28, although the force of the date indicator driving finger 930 exerted to the date indicator 920 is slightly reduced, the force for rotating the date indicator 920 stored to the date indicator driving finger 930 is much larger than the force necessary for rotating the date indicator 920 (that is, the date indicator feeding resistance) and therefore, rotation of the date indicator 920 is not stopped.
When the date indicator driving wheel 906 and the date indicator driving finger 930 are further rotated further from the state shown in FIG. 33, the date indicator driving finger 930 rotates the date indicator 920 in the direction shown by the arrow mark. Under the state, the clearance 931b between the inner peripheral portion of the spring portion 932 of the date indicator driving finger 930 and the outer peripheral portion of the central portion 931 stays to be widened. When the intersection of the first setting portion 942a and the second setting portion 942b of the date jumper 940 passes the linear portion of the trapezoidal tooth tip of the second tooth 920g from the state shown in FIG. 33, the date indicator 920 is further rotated in the direction shown by the arrow mark by spring force of the date jumper spring portion 944 of the date jumper 940. Further, the date indicator feeding resistance becomes “0”. When the date indicator 920 is rotated further from “state of point E” in FIG. 28, the force of the date indicator driving finger 930 exerted to the date indicator 920 is further reduced. According to the conventional calendar mechanism, the date indicator 920 can be rotated by an amount of one date by rotating the date indicator driving wheel 906 by about 9.6 degrees. That is, according to the conventional calendar mechanism, a date feeding time period is about 36 minutes.
(4•4) Operation of Date Correction:
In reference to FIG. 26, in carrying out date correction, when the winding stem 910 is rotated in the first direction in the state in which the winding stem 310 is disposed at 1 stage, the date corrector setting transmission wheel 912 is rotated in a direction shown by an, arrow mark. When the date corrector setting transmission wheel 912 is rotated in the direction shown by the arrow mark, the date corrector setting wheel 914, is moved to the first position pivoted in one direction (position at which the date corrector cam 916 is brought in mesh with the inner teeth portion 920a of the date indicator 920). When the date corrector setting wheel 914 is disposed at the first position pivoted in one direction, the date corrector cam 916 is brought in mesh with the inner teeth portion 920a of the date indicator 920. By rotating the winding stem 910 in the first direction under the state, date correction can be carried out by rotating the date indicator 920 in a direction shown by an arrow mark.
As shown by FIG. 27, although a front end of the date corrector cam 916 is sharpened, there is a linear portion at a front end of the inner teeth portion 920a of the date indicator 920 and therefore, there is a concern that the front end of the date corrector cam 916 and the linear portion of the front end of the inner teeth portion 920a of the date indicator 920 interfere with each other.
When the winding stem 910 is rotated in the second direction reverse to the first direction in the state in which the winding stem 910 is disposed at 1 stage, the date corrector setting transmission wheel 912 is rotated in a direction reverse to the direction shown by the arrow mark. When the date corrector setting transmission wheel 912 is rotated in the direction reverse to the direction shown by the arrow mark, the date corrector setting wheel 914 is moved to the second position pivoted in other direction (position at which the date corrector cam 916 is not brought in mesh with the inner teeth portion 920a of the date indicator 920). Even when the winding stem 910 is rotated in the second direction, the date indicator 920 is not rotated and date correction cannot be carried out.
However, the following problems are associated with the conventional calendar mechanisms of the timepieces with calendar.    (1) According to the conventional calendar mechanism disclosed in patent literature 1, a long period of time exceeding one hour is needed for feeding the date indicator.    (2) According to the conventional calendar mechanism disclosed in patent literature 2, shapes of parts are complicated, very high machining accuracy of parts is requested and a long period of time is needed for fabricating, assembling and adjusting of parts.    (3) According to the conventional calendar mechanism disclosed in nonpatent literature 1, a number of parts are needed. Further, a long period of time is needed for fabricating, assembling and adjusting of parts.    (4) According to the other conventional calendar mechanism shown in FIG. 24 through FIG. 33, since the shape of the tooth of the date indicator is trapezoidal, when date correction is carried out, there is present a long dead point (time band at which date correction cannot be carried out). Further, according to the calendar mechanism, when the date indicator correcting mechanism of the pivoting type is used, there is brought about a phenomenon in which the corrector tooth of the date corrector setting wheel interferes with the straight portion of the tooth of the date indicator and the date correction cannot be carried out.